Drogue with power generator

ABSTRACT

In one embodiment an aerial refueling drogue comprises a coupling having a channel formed therethrough, a shroud, and a piezoelectric energy collection system. Other embodiments may be described.

BACKGROUND

The subject matter described herein relates to refueling drogues. Moreparticularly, the disclosure relates to refueling drogues which includepower generation capabilities which may be used to power a controlsystem for the drogue.

In order to extend the flight range of certain aircraft, some aircrafthave been designed with in-flight refueling or air-to-air refuelingcapabilities. One type of refueling system is a hose and drogue system.The hose and drogue system includes a refueling hose having a droguedisposed at one end. A drogue is a funnel shaped device attached to theend of a refueling hose for connecting with the probe of anotheraircraft to be refueled in flight. The refueling hose connects to a HoseDrum Unit (HDU). When not in use, the refueling hose and drogue isreeled completely into the HDU. During operation, the refueling tankerflies straight and level and extends the refueling hose and drogue whichtrails behind and below the refueling tanker under normal aerodynamicforces. Tension on the refueling hose is aerodynamically balanced by amotor in the HDU so that as the receiver aircraft moves, the refuelinghose retracts and extends in order to prevent bends in the refuelinghose that may cause undue side loads on the refueling probe.

The second type of refueling system is a boom refueling system. The boomrefueling system typically includes a rigid boom extending from therefueling tanker, with a probe and nozzle at its distal end. The boomalso includes airfoils controlled by a boom operator stationed on therefueling aircraft. The airfoils allow the boom operator to activelymaneuver the boom with respect to the receiver aircraft, which flies ina fixed refueling position below and aft of the tanker aircraft.

Although in-flight refueling is a relatively common operation, theaircraft to be refueled must be precisely positioned relative to therefueling tanker in order to provide safe engagement while the fuel isdispensed to the receiver aircraft. Different systems have been designedto automate the positioning process. For example, some boom refuelingsystems use cameras housed in the tanker aircraft to determine thedistance between the receiver aircraft and the tip of a refueling boomcarried by the tanker aircraft. The camera system can then be used toautomatically control the position of the boom to mate with acorresponding refueling receptacle of the receiver aircraft.

In another system, a drogue can include movable, overlapping vanes and acanopy. The vanes may be moved to increase or decrease the size of thediameter of the drogue for high speed flight or for lower flight speeds.The drogue may include actuators to control the motion of the vanes andor the canopy. The motion of the actuators may be controlled by aguidance and control system. The guidance system can receive informationcorresponding to the current state of the drogue and a target state ofthe drogue. The guidance system can provide instructions to the controlsystem that in turn directs the actuators to drive the configuration ofthe drogue from the current state to the target state.

The use of aerial refueling systems may be expanded if the refuelingdrogue had the ability to generate and store electrical power that couldbe used to run guidance and control systems of the refueling system.This would allow aerial refueling drogues to be retrofitable by boltingon to the end of the refueling hose of existing aerial refueling systemssuch as Wing Aerial Refueling Pods (WARPs) or Fuselage Hose Drum Units(HDUs). However, present refueling drogues do not have the ability togenerate and store its own electrical power which to run the guidanceand control systems.

Onboard wind mill generators located on the external surface of a droguehave been proposed to generate a small amount of power to helpilluminate the drogue so the receiver aircraft pilot can see it duringnight refueling. However, wind mill generators are inefficient and maynot be able to generate sufficient amounts of power to run guidance andcontrol systems of the refueling system. These types of generators alsotake up valuable space under the drogue cowling, space that is neededfor the guidance and control system.

Onboard battery packs have also been proposed to provide for acontrollable drogue power system. However, battery packs only have alimited supply of power before needing to be recharged. In thesesystems, when the battery packs needed to be recharged, the drogue wouldhave to be retracted back into the aerial refueling pods or HDU of thehost aircraft. Once the batteries were recharged, the drogue could bere-extended to refuel again. This is a time consuming process.Furthermore, if the battery packs were to be depleted of power sometimeduring the refueling process, this could be problematic for therefueling tanker and the aircraft to be refueled.

SUMMARY

In various aspects, aerial refueling drogues which include piezoelectricpower systems are described. In one embodiment an aerial refuelingdrogue comprises a coupling having a channel formed therethrough, atleast one flexible fin disposed on a surface of the coupling, and atleast one piezoelectric patch disposed on the flexible fin.

In another embodiment a method to provide electrical power to an aerialrefueling drogue is provided. The aerial refueling drogue comprises aplurality of piezoelectric patches disposed on flexible member. Themethod comprises deploying the aerial refueling drogue into an airstreamand harvesting energy produced by the piezoelectric patches.

In another embodiment an aerial refueling drogue comprises a couplinghaving a channel formed therethrough, a shroud, and a piezoelectricenergy collection system.

The features, functions and advantages discussed herein can be achievedindependently in various embodiments described herein or may be combinedin yet other embodiments, further details of which can be seen withreference to the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures.

FIG. 1 is schematic illustration a of a tanker aircraft using acontrollable aerial refueling drogue having a self-contained electricalgenerator for refueling a receiver aircraft, according to embodiments.

FIG. 2A is a schematic, side-view illustration of a refueling drogue,according to embodiments.

FIG. 2B is a cross-sectional view illustration of a coupling for arefueling drogue, according to embodiments.

FIG. 3A is a schematic, side-view illustration of a fin for a refuelingdrogue, according to embodiments.

FIG. 3B is a cross-sectional view illustration of a fin for a refuelingdrogue, according to embodiments.

FIG. 4A is a schematic, side-view illustration of a strut for arefueling drogue, according to embodiments.

FIG. 4B is a cross-sectional view illustration of a strut for arefueling drogue, according to embodiments.

FIG. 5 is simplified block diagram illustrating components of a powersystem for a refueling drogue, according to embodiments.

FIG. 6 is a flowchart illustrating operations in a method to provideelectrical power to an aerial refueling drogue

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth toprovide a thorough understanding of various embodiments. However, itwill be understood by those skilled in the art that the variousembodiments may be practiced without the specific details. In otherinstances, well-known methods, procedures, and components have not beenillustrated or described in detail so as not to obscure the particularembodiments.

FIG. 1 is schematic illustration a of a tanker aircraft using acontrollable aerial refueling drogue having a self-contained electricalgenerator for refueling a receiver aircraft, according to embodiments.Referring to FIG. 1, a refueling system 110 is shown. The refuelingsystem 110 may include a tanker aircraft 100 which is positioned to becoupled to a receiver aircraft 104 which needs to be refueled using anaerial refueling device 120.

In the embodiment shown in FIG. 1, the tanker aircraft 100 may have afuselage 101, wings 102, and one or more engines 103. The tankeraircraft 100 shown in FIG. 1 is shown as an example and the tankeraircraft 100 may take on other forms. The tanker aircraft 100 may havean aerial refueling device 120 attached thereto. The aerial refuelingdevice 120 may include an on-board portion 122 and a deployable portion121. In accordance with one embodiment, the on-board portion may have ahose reel actuator and associated valves. The deployable portion 121 mayinclude a hose 123 and a drogue 124.

The position of the drogue 124 may be controlled in an automatic fashionto align and couple with a probe 105 of a receiver aircraft 104. In atleast some embodiments, the guidance and control system for effectuatingthe alignment and control may be carried entirely by the deployableportion 121 of the refueling device 120. Accordingly, not only can theprocess for coupling the drogue 124 to the receiver aircraft 104 beautomated or at least partially automated, but the components thatexecute the automated process need not be carried on-board the tankeraircraft 100. This arrangement can simplify the tanker aircraft 100 andcan significantly reduce the effort and expense required to retrofit theguidance system on an existing drogue-carrying tanker aircraft 100.

As stated above, the use of refueling systems 110 may be expanded if thedrogue 124 had the ability to generate and store electrical power thatcould be used to run the guidance and control systems. This would allowaerial refueling drogues to be retrofitable by bolting on to the end ofthe refueling hose of existing aerial refueling systems.

In some embodiments the drogue 124 may be implemented as a controllabledrogue as described in commonly assigned U.S. Pat. No. 7,219,857 toTakacs, et al., or as in commonly assigned U.S. patent application Ser.No. 12/265,449 to Steko, et al., (U.S. Patent Publication No:20100108815 A1) the disclosures of which are incorporated herein byreference in their respective entirety. In other embodiments the drogue124 may be a passive drogue. A controllable drogue 124 may utilize apower source to provide electrical power for the control system for thedrogue 124. A passive drogue 124 may utilize a power source to providepower for an illumination system or a beacon system. Thus, powersupplies for drogues find utility in both controllable drogues andpassive drogues.

Described herein are aerial refueling drogues which are adapted toinclude a piezoelectric power supply system, and methods of using suchdrogues. In the interest of brevity, passive aerial refueling droguesare described herein. However, one skilled in the art will recognizethat piezoelectric power supply systems may be implemented incontrollable drogues such as those described in U.S. Pat. No. 7,219,857to Takacs, et al and U.S. Patent Publication No: 20100108815 A1 toSteko, et al.

One embodiment of a drogue assembly is presented in FIGS. 2A-2B. FIG. 2Ais a schematic, side-view illustration of a refueling drogue, accordingto embodiments. FIG. 2B is a cross-sectional view illustration of acoupling for a refueling drogue, according to embodiments. ReferringFIGS. 2A and 2B, in some embodiments an aerial refueling drogue assembly200 comprises a coupling 220 adapted to mate with a hose 123, asdescribed above. The coupling 220 comprises a channel 222 through whichfluids (e.g., fuel) may pass. The channel 222 may of approximately thesame diameter as the hose 123 to which the coupling is connected. Drogueassembly 200 further comprises a shroud 250 which is supported by aplurality of struts 240, which forms what is sometimes referred to inthe art as the drogue basket.

The coupling 220 comprises a plurality of fins 230 which extend radiallyfrom the exterior surface of the coupling 220. In the embodimentdepicted in FIGS. 2A and 2B the coupling 220 comprises a total of eight(8) fins which extend longitudinally along the surface of the coupling220. One skilled in the art will recognize that more or fewer fins 230may be used. In the embodiment depicted in FIG. 2B the respective fins230 have a cross-sectional thickness that is tapered, i.e., thecross-sectional thickness is wider at the bottom than the top. Thespecific size of the fins 230 is not critical. In some embodiments thefins 230 may measure between approximately 1 inches and 4 inches (i.e.,2.5 to 10 centimeters) in height and 1 inches and 6 inches (i.e., 2.5 to15 centimeters) in width. The thickness of the fins 230 may vary between0.02 inches and 0.10 inches (i.e., 0.05 to 0.25 centimeters).

Further one or more of the struts 240 may comprise a fin 242 extendingalong the longitudinal extent of the strut 240. The fins 242 may have across-sectional thickness that is tapered, i.e., the cross-sectionalthickness is wider at the bottom than the top. The specific size of thefins 242 is not critical. In some embodiments the fins 242 may measurebetween 16 inches and 24 inches (i.e., 32 to 60 centimeters) in lengthand 1 inches and 5 inches (2.5 to 12.5 centimeters) in width. Thethickness of the fins 230 may vary between 0.02 inches and 0.3 inches(0.05 to 0.75 centimeters).

The fins 232, 242 may be formed from a flexible material, e.g., apolymer, rubber, or the like, which enables the fins to deform, orflutter, when the drogue is placed into an airstream. Optionally, ashroud (not shown) may be positioned around the fins 232 in a mannersimilar to the shroud 250.

In some embodiments one or more of the fins 232 may comprise apiezoelectric patch disposed on a surface thereof to generate electricalcurrent in response to the motion of the fins 232. FIG. 3A is aschematic, side-view illustration of a fin for a refueling drogue,according to embodiments, and FIG. 3B is a cross-sectional viewillustration of a fin for a refueling drogue, according to embodiments.Referring to FIGS. 3A and 3B, in one embodiment a piezoelectric patch234 is secured to each opposing side of the fin 232, such thatdeformation of the piezoelectric patches 234 created by the motion ofthe fin 232 generates an electrical current in each of the piezoelectricpatches 234.

Similarly, one or more of the fins 242 may comprise one or morepiezoelectric patches 244 on a surface thereof to generate electricalcurrent in response to the motion of the fins 242. FIG. 4A is aschematic, side-view illustration of a strut for a refueling drogue,according to embodiments. FIG. 4B is a cross-sectional view illustrationof a strut for a refueling drogue, according to embodiments. Referringto FIGS. 4A and 4B, in one embodiment a piezoelectric patch 244 issecured to each opposing side of the fin 242, such that deformation ofthe piezoelectric patches 244 created by the motion of the fin 242generates an electrical current in each of the piezoelectric patches244.

Electricity generated by the respective piezoelectric patches 234, 244may be directed into an energy collection system. FIG. 5 is simplifiedblock diagram illustrating components of an energy collection system 500for a refueling drogue, according to embodiments. Referring to FIG. 5,in some embodiments the energy collection system 500 comprises aplurality of piezoelectric patches 500, which may correspond to thepatches 234, 244. The patches 510 generate alternating current (AC)electricity, which is input into an AC/DC converter 510 to convert theAC electricity to a direct current (DC) electricity. The DC electricitymay be input into a voltage regulator 530 to produce electricity of adesired voltage, which is stored in an energy storage medium 540, e.g.,a battery pack.

FIG. 6 is a flowchart illustrating operations in a method to provideelectrical power to an aerial refueling drogue 200. Referring to FIG. 6,at operation 610 a drogue 200 is deployed. In some embodiments thedrogue assembly 200 may be deployed by releasing the drogue 200 from atanker aircraft such that the drogue 200 is places into the airstream.When the drogue is deployed into the airstream the fins 232, 242 flutterin the airstream, which causes the respective piezoelectric patches 234,244 to generate electricity.

At operation 615 the electrical from the piezoelectric patches 234, 244is harvested, e.g. by directing the electrical energy into the AC/DCconverter 520 and the voltage regulator 530. At operation 620 theelectrical energy generated by the piezoelectric patches is stored inthe energy storage medium 540.

Reference in the specification to “one embodiment” or “some embodiments”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least animplementation. The appearances of the phrase “in one embodiment” invarious places in the specification may or may not be all referring tothe same embodiment.

Although embodiments have been described in language specific tostructural features and/or methodological acts, it is to be understoodthat claimed subject matter may not be limited to the specific featuresor acts described. Rather, the specific features and acts are disclosedas sample forms of implementing the claimed subject matter.

1. An aerial refueling drogue comprising: a coupling having a channelformed therethrough; at least one flexible fin disposed on a surface ofthe coupling; and at least one piezoelectric patch disposed on theflexible fin, wherein the drogue comprises: a shroud; and a plurality ofstruts coupled to the shroud, wherein at least one strut comprises aflexible fin.
 2. The aerial refueling drogue of claim 1, wherein the atleast one flexible fin comprises a piezoelectric patch disposed on asurface thereof.
 3. The aerial refueling drogue of claim 1, furthercomprising an energy storage device coupled to the piezoelectric patch.4. The aerial refueling drogue of claim 3, further comprising a powerconverter coupled to the piezoelectric patch.
 5. The aerial refuelingdrogue of claim 4, further comprising: a voltage regulator coupled tothe power converter; and a power storage device coupled to the voltageregulator.
 6. The aerial refueling drogue of claim 5, wherein power fromthe power storage device is used to power at least one of a camera or anillumination source coupled to the drogue.